An unindicted co-conspirator is a person who is identified by a law enforcement officer to have engaged in a conspiracy, but who is not charged in the indictment charging that person’s fellow conspirators. Prosecutors may name persons as unindicted co-conspirators for: grants of immunity, pragmatic considerations, and evidentiary concerns. The term unindicted co-conspirator was familiarized in 1974.
The term ‘co-conspirator’ is not different from the ‘conspirator’. Therefore an unindicted co-conspirator is also known as unindicted conspirator. Although the use of unindicted co-conspirators in not prohibited by law, the United States Attorneys' Manual generally recommends against naming unindicted co-conspirators.